An improved apparatus and method for increasing thru-put of electron beam lithography systems employing direct electron beam writing is disclosed in co-pending U.S. application Ser. No. 749,796 filed June 28, 1985 entitled "Multiple Channel Electron Beam Optical Column Lithography System and Method of Operation"--Kenneth J. Harte, inventor and assigned to Control Data Corporation. In this new system it is possible to directly write with more than one electron beam in parallel on a single substrate semiconductor wafer. To accomplish this, the diameter of the individual electron-optical columns which are clustered over a single target semicoductor wafer must be significantly smaller than that of the wafer itself in order to accommodate a sufficient number of electron-optical columns in the cluster to provide the desired increase thru-put. Theoretically, electron optical columns designed with all electrostatic optics can meet this requirement. However, each electron optical column must employ component structures which keep the components in alignment both axially and rotationally, and the cluster of electron-optical columns forming the multi-channel assembly must be mechanically referenced to each other and provided with many electrical connections that have to be brought through a vacuum-tight wall without impairment of the vacuum within the housing in which the assembly of electron beam optical columns is mounted.
In a typical multi-beam system employing a multiplicity of single beam electron-optical channels, the channels must be mounted on 40 milimeter centers in a square or rectalinear array. Mechanical support, alignment and wiring must be provided for each of the individual electron-optical columns comprising the respective channels within the 40 millimeter center to center spacing. This involves approximately 400 electrical connections between the channels and the external control and supply electronic circuits so that the use of known discrete wiring techniques to supply the individual channels is impossible. In order to overcome these problems the present invention was devised.